Sustainable solvents and extraction techniques in green analytical chemistry for determination of emerging and inorganic contaminants in environmental samples

Abstract

There is an increase in the occurrence of several substances used worldwide that represent an imminent or potential risk to human and environmental life, as a result of this risk, they have been indicated as Emerging Contaminants (EC). Consequently, there are intensified efforts to develop techniques for the analysis of ECs, based on the principles of Green Analytical Chemistry (GAC), including the miniaturization of methods, reduced consumption of reagents and energy, and avoidance of the use of toxic compounds. The development of green solvents provides an example of the production of new sustainable materials based on the principles of GAC. The present research project proposes the synthesis of Natural Deep Eutectic Solvents (NADES) and amino Acid-based Deep Eutectic Solvents (AADES) with the components ²-alanine, tryptophan, carboxylic acids (malic acid and citric acid), and carbohydrate (xylitol), as well as the synthesis of Hydrophobic Deep Eutectic Solvents (HDES) based on DL-menthol, acetic acid, and lactic acid, modified with magnetic Fe3O4 Nanoparticles (NPs). Three synthesis methods will be evaluated: controlled heating and stirring, Ultrasound-Assisted Synthesis (UAS), and microwave-assisted synthesis (MAS). Characterization techniques employed to investigate the formation of these new solvents will include Infrared Spectroscopy (IR), Thermogravimetry (TG), and Differential Scanning Calorimetry (DSC), together with polarity, density, and viscosity measurements. These new solvents will be evaluated as extraction solvents in green sample preparation methods for use in environmental monitoring of ECs belonging to the classes of pharmaceuticals and brominated flame retardants, present in samples of surface water, industrial effluent, and sewage sludge. These analytes will be determined by Gas Chromatography coupled to Mass Spectrometry (GC-MS). In addition, the elements As, Cd, Cr, Hg, Se, and V will be analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). These analyses will be accompanied by assessment of the possible interferences inherent to the techniques. Finally, metric tools will be used to evaluate the solvent synthesis processes and the analyte extraction methods, considering their green characteristics and compliance with environmental criteria. (AU)